In 1793-94, a three-volume, 700-page Treatise on Insanity by Vincenzo Chiarugi (1759-1820) appeared in Florence. No translation in English or in any other language of this important work has ever appeared. The book is exceedingly rare and difficult to read and understand, even by scholars well versed in Italian. An English translation of the book, currently being prepared under the sponsorship of the National Library of Medicine is incomprehensible and needs extensive revision. This translation is in process and should be terminated by the end of 1981. Chiarugi's name is traditionally associated with Pinel's in France and W. Tuke's in England, as the three men who initiated reforms in the treatment of the mentally ill, which led to the development of modern psychiatry. While Pinel's and W. Tuke's works have been thoroughly studied, however, Chiarugi's has remained virtually unaccessible. Yet, his work is very significant, especially when viewed in the context of the Enlightenment movement in Tuscany in the late 18th century, under the rule of the Grand Duke Peter Leopold who introduced there all kinds of reforms. Chiarugi worked as head physician of the Hospital Bonifacio in Florence for 30 years. Under his leadership, the Regulations of the hospital, containing pioneering views for the treatment of the insane, were published in 1789. The Treatise on Insanity contains a description of insanity in general and its specific forms, of the treatment of insanity, and of one hundred clinical reports. The main thrust of the book lies in the strong stance against any cruel restrictions of patients, for whom confidence and patience by the staff are advocated. Although Chiarugi did not claim any significant advance or new therapeutic approach, his views were truly revolutionary. The principal investigator published various articles on Chiarugi's work during the past 25 years. His aim is to prepare an easy to read English translation of On Insanity with notes and explanations to Chiarugi's texts and quotes. A 50- to 100-page introduction will be added, helping to place Chiarugi's work in the context of his time and to fill a gap in modern historiography of psychiatry. It is expected that the translation will be considered for publication under the National Library of Medicine Special Foreign Program with distribution either through the National Technical Information Service (NTIS) or a USA University press.